(1)α alloy and near α alloy.
(2)(α+β) alloy.
(3) beta alloy and near beta alloy.
The national standard uses TA instead of α alloy; TB represents beta alloy; TC stands for (α+β) alloy. For example, TA 1 is industrially pure titanium; TB 1 is β titanium alloy; TC4 is (α+β) titanium alloy. Most of the newly trial-produced alloys directly follow American standards and are expressed by alloy elements and content. For example, Ti- 1023 alloy is based on titanium and contains 10% vanadium, 2% iron and 3% aluminum.
The annealing structure of (α+β) titanium alloy consists of (α+β) two phases. It has the advantages of both α and β titanium alloys, that is, high heat resistance and easy hot working, and can be strengthened by heat treatment. The advantage of (α+β) alloy is that the microstructure of the alloy, that is, the properties and proportion of α phase and β phase can be changed in a wide range, from near α type to near β type alloy to meet different design and use requirements.
In terms of composition, (α+β) alloys are generally based on Ti-Al, and appropriate β stabilizing elements are added. Because most of the alloy elements with practical value in the periodic table belong to β stable components, the selection of (α+β) type alloy components far exceeds that of α type alloys. For example, the (α+β) titanium alloy specified in China's metallurgical standards belongs to:
Titanium aluminum manganese series: TC 1(Ti-2Al- 1.5Mn), TC2(Ti-3Al- 1.5Mn).
Ti-Al-V series: TC3(Ti-5Al-4V), TC4(Ti-6Al-4V), TC10 (Ti-6al-6v-2sn-0.5cu-0.5fe).
Ti-Al-Cr series: TC5(Ti-5Al-2.5Cr), TC6 (Ti-2-5.5al-2cr-1Fe-2mo).
Ti-Al-Mo series: TC8 (Ti -6.5 Al -3.5 Mo -0.25 Si) and TC9 (Ti -6.5 Al -3.5 Mo -2.5 Sn -0.3 Si).
TC 1 1 (titanium -6.5 aluminum -3.5 molybdenum-1.5 zirconium -0.25 silicon)
Among them, TC 10 is a high-strength titanium alloy, and TC6, TC8, TC9, TC 1 1 are hot-strength titanium alloys, and the working temperature is 400 ~ 500℃.